Importance of line stage pre--Who Knew?


Well, I'm sure a lot of you knew, or there would be no $5K and up market for line stages.

As for me... This month marks the 40th anniversary of buying my first stereo with my own money. In all that time I've only had solid state in the signal chain except for a Jolida phono preamp and matching line stage I picked up a couple of years ago. It turns out that the tubes in those units were for a buffer stage to warm up the sound, while the gain was handled by op amps. Well, recently an audio buddy came by to spin some vinyl and show me a tube-driven line stage preamp he wanted to sell.

See it here.

This is just a simple, modest line stage preamp with 5-input rotary selection knob, balance, and volume. Five pairs of inputs, one fixed and two volume-controlled pairs of outputs on the back. However, it's a PTP hand-wired design with tube rectifier and large transformer. I didn't want to like it as it had a couple of deal-killers: 1) no remote control and 2) too tall to fit on my audio rack thanks to that outsize transformer. It would have to be a game-changer for me to consider getting it.

We tried it out in the humblest of circumstances. I set it on a Rubbermaid step stool in front of my rack and patched it into the signal path, bypassing the Jolida op amp/tube buffer line stage.

HOLY MOLY!

Game changer? Sh'yeah! After just a few seconds of hearing it you know it's not leaving the house. So what did it do?

It simply sounded more real and less electronic. It heightened the illusion of performers in real space making music. It took my system a big step away from a tune player to a sonic virtual reality device. Sonically the difference might be considered subtle, but in the realm of emotional response to the music, it was a big step. There was more separation between the various elements of the mix, and if you sat in the sweet spot between the speakers, you heard a 3-dimensional image of performers spread out before you. That physical separation also separates into audible separation. It was easier to hear how the musicians interact with each other to make music together--just like in a live performance. Instead of an amorphous left-to-right smear there was a sonic hologram of where the performers stood in the mix. However, this did not desconstruct the performance, but rather showed how the elements worked together to form ensemble music.

Timbres sounded more real: Brass had more blat when called for, more sense of air flowing through metal, of lungs full of air providing the energy for the resulting sound. Strings sounded pluckier, voices more human, acoustic instruments woodier... you get the picture. It made LPs sound enveloping with a nicely laid-out soundstage, and it elevated computer-based digital music from tolerable to involving and enjoyable, again with the 3-D imaging and wider-than-the-speakers sound stage.

Before picking up this piece, I was thinking of upgrading amplifiers yet another time. But I experienced a valuable lesson I had previously known more in theory--that for fine gradations of amplitude, tubes rule, and it's the low level--preamp and component level--signals that are most fragile; if part of the signal drops out at that stage, no amplifier will bring it back regardless of the amp's bandwidth, rise time, signal-to-noise ratio, or resolving power. The preamp has to caress and amplify those low level signals and pass them on to the amplifier so you can groove to them when they exit the speakers. Since all my sources--LP, CD, FM, iPod, and computer--run through this unit, everything sounds better,

In fact, one of the things I learned from this experience is that my $220 used 1981 Heathkit amplifier is even better than I thought. Paired with this preamp, it is still superb. Sure there are better and much better. But for now and some time to come, it'll do nicely.

Since picking it up I swapped in a set of Sylvania NOS tubes--a JAN (mil-spec) 6X5WGT rectifier (smoother delivery and better voltage regulation) and a matched set of '50s-era Sylvania 6SN7GTB triodes (even more liquidity, less grain, more 3-D imaging). I'm a happy man. Next up--sell off some electronics and get a tube phono stage from this maker.
johnnyb53
I have a really refined system, one that I've made countless improvements in from power delivery to chassis tuning to optimization of cabling...

It's really interesting because I have two systems and one uses a tube amp and preamp while the other uses an all-digital electronics chain. They both use power regenerators and similar cabling and both sound outrageously good.

That being said, in my view the all-digital system has the edge in dynamics and transient speed and it also sounds the most natural or realistic if your reference is live acoustic instruments including the human voice.

I have a truly excellent dual-mono 6SN7 tube line stage that I can instantly switch in and out of the all-digital system between the digital preamp and digital power amp and in the past, with certain combinations of cabling and AC filtering products it has made a marginal improvement in smoothness and musicality over a direct Balanced XLR connection. Although the improvement of the 6SN7 pre was small, I thought it worth having.

But recently, I added the PS Audio P3 Power Plant, Mojo Audio AC power cords on the preamp and amp, and the Wyred 4 Sound C2 Balanced XLR interconnects between the preamp and power amp. I did this in individual steps and each time I inserted a different piece, starting with the PS P3 Power Plant and adding in the different power cords and finally the interconnects and found there was an improvement in musicality, inner detailing and musical bloom.

In my recent comparisons between the direct XLR connection and the tube line amp connection there is less of a difference and in fact the XLR connection offers slightly better dynamic punch and clarity with the same level of musicality. So at this point I'm thinking of removing the tube buffer entirely.

I still love my tube system for its great musicality and smoothness but for true musical realism I favor my evolved all-digital chain.

I think tubes provide smoothness in systems that have other problems that need to be masked. But once you eliminate the problems that cause grain and harshness, really good digital or solid-state electronics can provide a musical experience that is as good or even better than tubes. And I can listen to this system at a very healthy volume for hours without any listener fatigue.

My main problems with tubes (besides the inevitable tube rolling) is their treble and bass roll off at the extremes, their slight rounding of fast transients, and their inevitably higher noise floor. This translates into a smooth and musical but more muddled and less resolving musical presentation that can be had from the best solid-state or digital gear IMHO. YMMY, and I realize that many folks prefer a sweet, relaxing presentation that loses some detail and articulation in the process.
...a bit of a caveat......most changes (subtle, grand, good, bad) are perceived as a "Wow". Live with this new one for a few weeks and discover ITS warts...you just might want to go back to your old one.
I don't think so Stringreen. I've been in this hobby 40 years and have been a reviewer for over 15 years so I have a lot of experience with such things.

All I know is that as my Mojo Audio power cords continue to break in, the sound is getting incrementally better and better. In fact, I have never heard digital high frequencies sound so much like the real thing!

I'm not sure I understand what you mean about going back to my "old one." My old one of what? If you mean the tube pre it's easily switched in and out. And incidentally, the tube pre usually works better with my turntable source because the highs are a bit more extended with the vinyl source and the tube pre knocks that down just a touch. But I need to try it again because I haven't played the turntable since I installed the new W4S XLR interconnects on Friday.

BTW, I'm from Tucson so if you ever get the urge to take a day trip it might be worth your while...

Frank ;-)
I respect plato`s opinion and he`s right YMMV.I`ve found the complete opposite result.High quality tube components(preamp and power amplifiers) are more resolving,honest,realistic and nuanced.They seem to be purer with audio signal propagation. They are capable of preserving the musical signal and allow that vital emotional connection and expression of music.Thus far in my personal experience SS/digital amplified signals just are incomplete and stripped of the inner detail subtle information,just does`nt sound as real life as high quality tube electronics.For some reason this observation does`nt hold up with source components(CD and DACs so far, gube vs SS),I don`t no why.
Just another man`s point of view. I know preference can go in either direction.I hear less masking and superior resolution with the tube gear.This is why they sound more natural and less HiFi character compared to SS/digital amplifying the signal,at least to my ears.The good thing is we all eventually find our own audio direction and solution. Johnnyb53`s revelation makes sense to me. I don`t believe he`d have quite this same reaction without 'good' tube components.There`ll always be two sides to this story.
Regards,
If the OP actually listed his system it would give a better context to understand his recent aural discoveries.

I also think Stringreen makes a good point.